Shuttle Liftoff Could Come In July 1987

NASA officials at Johnson Space Center in Houston have set up a tentative space shuttle launch schedule that calls for a mission in July 1987 followed by seven or eight flights over 12 months.

The space agency also is studying whether to change the trajectory of shuttle launches and whether the spaceplane should fly at a slower speed to reduce stress on the vehicle.

The tentative launch schedule was devised so that NASA can begin renegotiating a multibillion-dollar contract with a Rockwell International subsidiary that runs such things as mission control and astronaut training, said Eugene Kranz, mission operations director at Johnson.

The schedule takes a conservative approach, Kranz said, and assumes that NASA will want 45 days between each launch. Challenger lifted off on its last, ill-fated flight Jan. 28, less than two weeks after Columbia landed.

Kranz stressed that the schedule is very tentative and is only for use in planning. ''It's really our best judgment of what we think is the earliest time we can fly,'' Kranz said.

Rear Adm. Richard Truly, head of the shuttle program, said last week that he expects the first launch within 12 to 18 months from the Jan. 28 disaster. Chet Lee, customer service director at NASA headquarters in Washington, said he expects an official launch schedule in mid-May. He stressed that Kranz's schedule should not be considered official.

Kranz said the Challenger explosion has forced NASA to reanalyze the shuttle trajectory, including whether to ''soften the uphill powered flight phase,'' which comes at about 50,000 feet when the engines are ''throttled up'' to 104 percent of thrust.

Changing the angle at which the shuttle is launched and the speed at which it flies could make it safer, he said. But that won't be known for several more weeks when the analysis is complete, he said.

The shuttle's main engines perform most efficiently at 104 percent of thrust, which means 4 percent above its original design. NASA engineers have been working to boost the engines' capability to 109 percent, but crucial tests recently were delayed until next year because turbine blades split in a high-pressure pump.

Kranz said he based the planning schedule on the assumption that the first shuttle flight would carry a Tracking and Data Relay Satellite, a sophisticated communications satellite owned by NASA that is relatively simple to put in orbit. A TDRS satellite aboard Challenger was destroyed.

He also said he is assuming that one of the first shuttle missions will be devoted to the release of a planetary launch. The release of two such spacecraft had been scheduled next month.

Ulysses, which will explore the sun's poles, and Galileo, which will explore Jupiter, must be launched when Jupiter and Earth are on opposite sides of the sun. That happens for only two weeks every 13 months. The next opportunity would be in June 1987 -- after Kranz's assumed first launch. The next opportunity after that would be July 1988.